1. Field of the Invention
The present invention relates to an epitaxial growth method and more particularly, to a GaN epitaxial growth method.
2. Description of the Related Art
A substrate on which an epitaxial layer is formed using an epitaxial growth method may be bent and many crystalline defects may arise in the epitaxial layer due to lattice mismatch and a difference in coefficient of thermal expansion between the substrate and the epitaxial layer. Thus, it is necessary to overcome the above-described problems while forming a single crystalline semiconductor material layer using the epitaxial growth method.
U.S. Pat. No. 6,579,359 discloses a technique of using a porous buffer layer that absorbs internal stress. In this technique, the porous buffer layer is formed on a SiC substrate, and a crystalline layer is formed on the porous buffer layer. Since the buffer layer is porous, it absorbs stress induced by lattice mismatch.
However, since the porous buffer layer is formed using an anodization process, a conductive substrate should be employed, thus only limited kinds of materials may be used for the substrate. Also, the anodization method is very complicated and costly.